Truck Mounted Attenuators (TMAs) have been used for many years on our nation's highways to protect road workers in works zones and other areas adjacent to high speed traffic. These crash cushions are typically mounted to the back of a work truck or other shadow vehicle and then placed some distance behind the work being done. In this way they protect the road workers from errant vehicles that may have left the open travel lanes and would otherwise endanger the road workers. Likewise there may be road maintenance operations that require a slow moving shadow vehicle that is driven by one of the road workers. In this instance, the driver of the shadow vehicle is also protected by the Truck Mounted attenuator, should a vehicle impact it.
The road workers are not the only ones deriving benefits from a TMA. Drivers of errant vehicles also benefit, as the impact with the crash cushion may lessen the potential injuries from such an impact.
Crash cushions, such as those disclosed in U.S. Pat. No. 5,642,792 to June and U.S. Pat. No. 6,092,959 to Leonhardt, include cartridges supported by a support structure, which may be released and allowed to collapse, for example with complex trigger mechanisms or release cables that stabilize the systems and hold them rigid until they were impacted by an errant vehicle. Such systems may be expensive, being configured with multiple hinge points that require precise welding and machining, so that all of the hinge members are aligned appropriately during assembly.